A stent is a tissue support device that is inserted in order to open (and keep open) the lumen of a vessel, duct, tract, or tube within the body. It can be used to treat a condition whereby the lumen of a vessel becomes constricted (stenosis). In the urinary system, an example of stenosis is benign prostatic hyperplasia (BPH).
Conventional urethral stents exist in two major categories or types: self-expanding, and balloon-expanding. The latter type of stent can be positioned over the balloon end of a balloon catheter. The catheter-stent assembly can then be inserted into the lumen of the urethra, and then guided to a target site where it can remain implanted for months (or years). At the present time, the only available urethral stents are of the expanding metal type, and have yet to prove themselves for long term implant use. There is, therefore, considerable need for a non-metallic balloon-expandable urethral stent.
In order to prevent migration of the stent from its intended location in the vessel, the stent will contain an array of small plastic protrusions that emerge only upon expansion. However, endothelial tissue may grow into the outer surface of the stent and help to keep it in place.
If removal of the stent becomes necessary, it should be possible with minimal pain and/or discomfort, minimal risk of tissue insult or damage, and minimal procedural complexity.